Lightest frame for RPi2 + Navio?


I ordered my Navio kit and I should receive it soon.
In the meantime I’m looking at frames. I think I will buy first a Q450 like Igor did here.

Then, I’m thinking about racer frames. What would be the smallest and lightest frame I can use in conjunction with Navio ?
Anyone knows what is used on homepage photo with a small grey plastic frame ?

Thank you in advance

The frame on the homepage should be this one: